As is described in U.S. Patent Application No. 2017/0105350 to CNH America LLC, which is incorporated by reference in its entirety and for all purposes, a rotary threshing or separating system of an agricultural combine harvester includes one or more rotors which can extend axially (front to rear) or transversely (side to side) within the body of the combine, and which are partially or fully surrounded by a perforated concave. The crop material is threshed and separated by the rotation of the rotor within the concave. Coarser non-grain crop material such as stalks and leaves are transported to the rear of the combine and discharged back to the field. The separated grain, together with some finer non-grain crop material such as chaff, dust, straw, and other crop residue are discharged through the concaves and fall onto a grain pan where they are transported to the cleaning system. Alternatively, the grain and finer non-grain crop material may also fall directly onto the cleaning system itself.
In combines having a rotor operating within a concave formed as a rotor cage, it is known to provide a transition cone between a feeder housing and the rotor cage. The transition cone narrows along its length, from the upstream end to the downstream end of the cone. An auger flight operated by the rotor transports the cut crop material through the transition cone, from the feeder housing and to the rotor cage. It is known to provide helical vanes on the inside surface of the transition cone, to facilitate efficient transport of crop material through the transition cone. During use, the crop material tends to follow along the transition cone vane and is somewhat compressed against the inside surface of the narrowing cone.
Referring now to the drawings, and more particularly to FIG. 1, there is shown a conventional threshing and separating system 24. The threshing and separating system 24 generally includes a rotor 40 at least partially enclosed by and rotatable within a corresponding perforated semi-cylindrical rotor cage 42. The cut crops are threshed and separated by the rotation of rotor 40 within rotor cage 42, and larger elements, such as stalks, leaves and the like are discharged from the rear of combine 10. Smaller elements of crop material including grain and non-grain crop material, including particles lighter than grain, such as chaff, dust and straw, are discharged through perforations of rotor cage 42. Rotor 40 is shown in a representative sense in that rotor 40 may be more than one rotor 40 and may be oriented generally in line with the direction of travel of combine 10. Grain that has been separated by threshing and separating assembly 24 falls onto a grain pan and is conveyed toward cleaning system.
Rotor 40 includes a downstream portion having threshing elements 72, and an upstream portion defining an inlet auger 74 having an auger flight or flights 76. The cylindrically shaped rotor cage 42 includes a concave or concaves 78 operating together with threshing elements 72 of rotor 40 to separate grain from crop material. A transition cone 80 is connected to rotor cage 42 and defines an infeed to the threshing zone of rotor 40 and rotor cage 42. Transition cone 80 has a hollow conical shape including an inner cone surface 82 having a larger diameter at the upstream end 84 thereof and tapering to a smaller diameter at the downstream edge 86 thereof, thereby defining a decreasing inner circumference about the inner surface from upstream end 84 to downstream end 86. At least one and typically a plurality of helical or spiral vanes 88 is provided on the inner surface of transition cone 80. Inlet auger 74 operates within transition cone 80, and crop material is transferred through transition cone 80 under the force applied by rotating auger flight 76, the directional guidance provided by vanes 88 and the influence supplied by the tapering conical shape of transition cone 80.
In operation, the inlet of the rotor cage 42 experiences high wear due to the tight radial clearance between the rotor cage 42 and the rotor 40. What is desired in the art is greater clearance between the rotor 40 and the rotor cage 42 to allow for expansion of the crop material in that region, which would permit the grain to migrate to the outside of the crop material for better separation. Simply enlarging the rotor cage is not necessarily possible in all harvesters due to vertical clearance limitations within the harvester.